Transformer module and power module

ABSTRACT

The present disclosure provides a manufacturing process of a metal winding, where the manufacturing process includes: cutting a first metal copper foil to form a connector and a pin; performing insulation processing on a surface of at least one of the first metal copper foil and a second metal copper foil; bending the first metal copper foil to form a first metal winding to cover on a magnetic core; and covering the second metal copper foil at least partially on a surface of the first metal copper foil to form a second metal winding, and a pin of the first metal winding passes through the second metal winding.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Patent ApplicationSer. No. 17/818,980 filed on Aug. 11, 2022, which is a continuation ofU.S. patent application Ser. No. 16/671,158 filed on Oct. 31, 2019,which claims priorities to Chinese Patent Application No. 201811301174.6filed on Nov. 2, 2018 and Chinese Patent Application No. 201911035920.6filed on Oct. 29, 2019, and the disclosures of the above applicationsare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the field of transformer technologies,and more particularly to a transformer module and a power module.

BACKGROUND

With the improvement of human requirements for smart living, the demandfor data processing in society is growing. The global energy consumptionin data processing averagely reaches hundreds of billions or eventrillions of kilowatt-hour per year; and the area of a large data centermay be tens of thousands of square meters. Therefore, high efficiencyand high power density are the key indicators for the healthydevelopment of this industry.

The key unit of the data center is the server which usually includesdata processing chips on a motherboard including such as a centralprocessing unit (CPU), chipsets, a memory, and their power supply andother necessary peripheral components. As the processing capacity of aserver increases, the number and integration level of these processingchips also increase, which results in an increase in the volume andpower consumption of the server. Therefore, the power supply for thesechips (because it is on the same motherboard as the data processingchips, also referred to as the motherboard power supply), is expected tohave higher efficiency, higher power density and smaller volume tosupport the energy saving and space reducing requirements of the entireserver or even the entire data center. In order to meet the demand ofhigh power density, the switching frequency of the power supply is alsohigher and higher. The switching frequency of the low-voltage andhigh-current power supply in the industry is basically 1 Megahertz(MHz).

The transformers for low-voltage and high-current applications aremostly implemented by a multi-layer printed circuit board (PCB). FIG. 1Ais a side view of a transformer having a multi-layer PCB windingprovided by the prior art. For example, as shown in FIG. 1A, the windingis formed horizontally on the different layers of the PCB board, and thePCB board is usually sleeved on the magnetic columns of the core, sothat the magnetic columns are vertical or nearly vertical to the PCBboard, such that the magnetic columns are vertical or nearly vertical tothe respective winding layers on the PCB board. And the thickness W ofthe winding is parallel to the length direction of the magnetic column;and the width H of the metal winding is vertical to the length of themagnetic column. Due to the PCB winding process, H and W generallysatisfy the following relationship: H>10 W. In this PCB windingstructure, the winding on different layers are connected by vias, sincethe layers are vertical to the magnetic columns, the vias are parallelto the magnetic columns. The winding on the inner layer is generallyconnected to that on the outer layer and the pins on the surface of thePCB (not shown) through vias. Generally, for the less than 5V voltageand larger than 50 A current output applications, a transformer with atleast ten-layers PCB is needed. And the height of a ten-layer PCB isabout 2 mm. Thus the length of the via is long and the impedance of thevia is large, so the loss caused by the via is large. FIG. 1B shows thetop view of the winding on the right magnetic column of the core. InFIG. 1B, the winding on the same layer may be separated into severalconcentric circles with different diameters R_(1A), R_(2A), . . . ,R_(nA). Since the concentric circles have different diameters, they havedifferent impedances. So there is a problem of uneven currentdistribution of the winding on one layer.

FIG. 2 is a structural schematic diagram of a transformer module. Forconvenience of description, in the schematic diagram, the shape of thewinding, and the positional relationship between the winding and themagnetic core are specifically drawn, but the disclosure is not limitedthereto. If multiple wiring layers need to be provided, an insulatinglayer and a new wiring layer can be sequentially added outside thewiring layer. With reference to FIG. 2 , the dimension of the windingparallel to the longitudinal direction of the magnetic column is definedas W, and the thickness of the winding which is the dimension of thewinding vertical to the magnetic column of the magnetic core is H. WhenH and W satisfy the relationship: W>10H, we define this winding mannerof the winding as a winding having a foil structure. For a winding in afoil structure, different portions of the winding have almost the samedistance to the magnetic core, that is, the equivalent diameters ofdifferent portions e.g. R_(1B) and R_(2B) are almost the same. Thusequivalent impedance of different portions is almost the same. So thecurrent distribution of the winding in a foil structure is almost evenwhich reduces the winding loss greatly. Generally, the winding shown inFIG. 2 is made by a copper foil process that is the winding is made ofcopper foil by cutting or punching process. And in this structure, theoutput connectors of the winding, e.g. 21 and 22 are almost stretchedout from the sides of the winding to connect to the circuits (notshown). The output connectors are always centralized, which means veryfew of the connectors (e.g. only two connectors for each winding in FIG.2 ) are used to connect to the circuit. The very few of the connectorsstretching out from the sides of the winding makes the uneven currentdistribution on the joint part of the connectors and the other part ofthe winding. In addition, centralized output connectors always have longlength. Thus the loss of the connectors is large.

SUMMARY

The present disclosure provides a transformer module and a power module,thereby achieving better distribution of windings.

In a first aspect, the present disclosure provides a transformer module,including:

-   -   a magnetic core, a first wiring layer, a first insulating layer        and a second wiring layer being sequentially disposed on the        magnetic core from outside to inside;    -   a first metal winding, formed in the first wiring layer and        winded around the magnetic core in a foil structure;    -   the first insulating layer, at least partially covered by the        first metal winding;    -   a second metal winding, formed in the second wiring layer and        winded around the magnetic core in a foil structure, wherein the        second metal winding is at least partially covered by the first        insulating layer, and at least partially covered by the first        metal winding;    -   wherein, the transformer module further includes a first pin, a        second pin, a third pin, and a fourth pin, the first metal        winding includes a first end and a second end, the second metal        winding includes a first end and a second end, the first end and        the second end of the first metal winding respectively are        electrically connected to the first pin and the second pin, the        first end and the second end of the second metal winding are        electrically connected to the third pin and the fourth pin        through a first connector and a second connector respectively,        and both of the first connector and the second connector pass        through the first insulating layer.

In a second aspect, the present disclosure provides a power module,including:

-   -   the transformer module as described in the first aspect;    -   a switch module, the switch module is in contact with the first        side of the transformer module and is electrically connected to        the first pin and/or the second pin.

Since the transformer winding with the foil winded structure is coatedon the transformer magnetic column, the equivalent diameters ofrespective parts of a turn of the winding having the foil windedstructure are similar, and the equivalent impedances are similar,thereby achieving the better distribution of the winding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side cross-sectional view of a transformer using amulti-layer PCB provided by the prior art;

FIG. 1B is a top view of windings of the transformer using a multi-layerPCB of the FIG. 1A;

FIG. 2 is a schematic structural view of another transformer moduleprovided by the prior art.

FIG. 3A is a perspective view of a magnetic core in a transformer moduleprovided by an embodiment of the present disclosure;

FIG. 3B is a perspective view of the magnetic core shown in FIG. 3Aafter forming a second metal winding;

FIG. 3C is a perspective view of the module shown in FIG. 3B afterforming a first metal winding;

FIG. 3D is a perspective view of a transformer module provided by anembodiment of the present disclosure;

FIG. 3E is an electrical schematic diagram of each end of thetransformer module shown in FIG. 3C;

FIG. 3F is a perspective view of the winding of FIG. 3C with two pins;

FIG. 3G is a schematic diagram showing the relationship between theratio n of the length of the pin and the length of the winding and thewinding loss P;

FIG. 3H is a perspective view of the winding of FIG. 3C with a pluralityof pins;

FIG. 4A is a bottom view of the transformer module after forming a thirdmetal winding;

FIG. 4B is a bottom view of a transformer module provided by anembodiment of the present disclosure;

FIG. 4C is an electrical schematic diagram of each end of thetransformer module shown in FIG. 4B;

FIG. 5 is a bottom view of another transformer module provided by anembodiment of the present disclosure;

FIG. 6A and FIG. 6B are respectively electrical schematic diagrams ofeach end of a power module provided by an embodiment of the presentdisclosure;

FIG. 6C and FIG. 6D are respectively cross-sectional views of a powermodule provided by an embodiment of the present disclosure;

FIG. 6E is a bottom view of a switch module provided by an embodiment ofthe present disclosure;

FIG. 6F is a cross-sectional view of a power module provided by anembodiment of the present disclosure;

FIG. 7 is an electrical schematic diagram of each end of a power moduleprovided by an embodiment of the present disclosure;

FIG. 8 is a cross-sectional view of the transformer module taken alongline AA′ shown in FIG. 5 according to an embodiment of the presentdisclosure;

FIG. 9A is a cross-sectional view of a transformer winding in anembodiment of the present disclosure;

FIG. 9B is a cross-sectional view of a transformer winding in anembodiment of the present disclosure;

FIG. 9C is a bottom view of a transformer in an embodiment of thepresent disclosure;

FIG. 9D is a bottom view of a transformer in an embodiment of thepresent disclosure;

FIG. 9E is a schematic view of a portion of a transformer taken alongthe dashed line in FIG. 9C and the switch modules disposed thereon;

FIG. 9F is a cross-sectional view of a power module in an embodiment ofthe present disclosure;

FIG. 10A is cross-sectional view of a transformer in an embodiment ofthe present disclosure;

FIG. 10B is a plan view of a winding in an embodiment of the presentdisclosure;

FIG. 10C is a perspective view of a winding in an embodiment of thepresent disclosure;

FIG. 10D is a perspective view of a winding in an embodiment of thepresent disclosure;

FIG. 10E is a perspective view of a winding in an embodiment of thepresent disclosure;

FIG. 10F is a perspective view of a winding in an embodiment of thepresent disclosure;

FIG. 10G is a schematic view of arrangement of pins in an embodiment ofthe present disclosure;

FIG. 10B-1 is a schematic cross-sectional view of a metal foil and aninsulating layer;

FIG. 10B-2 is a schematic cross-sectional view of the metal foil beforebending;

FIG. 10B-3 is a schematic cross-sectional view of the metal foil afterbeing bent;

FIG. 10B-4 shows the manufacturing process of the metal winding;

FIG. 11A and FIG. 11B are respectively structural schematic diagrams ofa transformer module provided by an embodiment of the presentdisclosure;

FIG. 12A is a cross-sectional view of a transformer module taken alongline AB of FIG. 11A provided by an embodiment of the present disclosure;

FIG. 12B is a cross-sectional view of a transformer module taken alongline AB of FIG. 11B provided by an embodiment of the present disclosure;

FIG. 13A is a top view of a transformer module provided by an embodimentof the present disclosure;

FIG. 13B is a top view of a transformer module provided by anotherembodiment of the present disclosure;

FIG. 14A is a bottom view of a transformer module provided by anembodiment of the present disclosure;

FIG. 14B is a bottom view of a transformer module provided by anotherembodiment of the present disclosure;

FIG. 15 is a cross-sectional view of a power module provided by anotherembodiment of the present disclosure;

FIG. 16 is a top view of a power module provided by another embodimentof the present disclosure.

FIG. 17 is a cross-sectional view of the transformer module taken aloneline BB′ shown in FIG. 5 according to an embodiment of the presentdisclosure.

FIG. 18 is a cross-sectional view of the transformer module taken aloneline CC′ shown in FIG. 5 according to an embodiment of the presentdisclosure.

FIG. 19 is a perspective view of a transformer module of FIG. 4Aaccording to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For the transformer for low-voltage and high-current applications, inthe prior art, it always adopts a PCB winding structure. In thestructure, the plane where the PCB board is located is vertical to themagnetic column, and the winding surrounding the magnetic column isformed by means of the trace on the PCB wiring layer. However, the PCBwinding structure will cause the equivalent diameters of the inner andouter sides of the trace of the metal winding of the wiring layer to beinconsistent, resulting in the equivalent impedance of the inner side ofthe winding being smaller than the equivalent impedance of the outerside of the winding, so that there is a problem of uneven distributionof the windings. Thus, when the transformer is used, the correspondingcurrent may be unevenly distributed.

While for the transformer with the foil winding structure in the priorart, the centralized output connectors of the winding are almoststretched out from the sides of the winding to connect to the circuits,which results in the uneven current distribution on the joint part ofthe connectors and the other part of the winding. And since thecentralized output connectors stretch out from sides of the windings,they always have long length. Thus the loss of the connectors is large.

In order to solve these technical problem, the present disclosureprovides a transformer module and a power module.

Embodiment 1

In one embodiment of the present disclosure, the windings in a foilstructure are formed in the wiring layer by, for example,electroplating, electroless plating, spray coating, dipping,electrophoresis, electrostatic spraying, chemical vapor deposition,physical vapor deposition, evaporation or printing. A plurality ofwiring layers may be disposed on the surface of the magnetic columns ofthe magnetic core, and an insulating layer is disposed between theadjacent wiring layers. The windings between the different wiring layersmay be connected through connectors, e.g. vias, passing through theinsulating layer.

FIG. 3A is a perspective view of a magnetic core in a transformer moduleprovided by an embodiment of the present disclosure; FIG. 3B is aperspective view of the transformer after forming a second metal windingon the magnetic core shown in FIG. 3A; FIG. 3C is a perspective view ofan embodiment of the present disclosure after forming a first metalwinding (bottom up) on the transformer module shown in FIG. 3B; FIG. 3Dis a perspective view by forming the ends (for example, asurface-mounted pin) on the transformer module shown in FIG. 3C, andFIG. 3E is an electrical schematic diagram corresponding to the pins ofthe transformer module shown in FIG. 3D. Referring to FIG. 3A to FIG.3E, the transformer module includes a magnetic core 31, a first metalwinding 33 (as shown in FIG. 3E, the first metal winding is, forexample, a secondary winding S2 of the transformer module) and a secondmetal winding 32 (as shown in FIG. 3E, the second metal winding is, forexample, the primary winding P of the transformer module).

In some embodiments, the magnetic core is

-shaped (that is, hollow square shaped), ring shaped, an I-shaped orC-shaped. For example, the magnetic core 31 shown in FIG. 3A is a

-shaped magnetic core. This disclosure does not limit the shape of themagnetic core.

The number of turns of the first metal winding (e.g. the secondarywinding S2) may be one turn or plural turns. For example, the number ofturns of the first winding 33 shown in FIG. 3C is one turn.

In some embodiments, the number of turns of the second metal winding(e.g. the primary winding P) may be one turn or plural turns. Forexample, as shown in FIG. 3B, the number of turns of the second winding32 is plural turns which forms a spiral type winding around a pluralityof magnetic columns of the

-shaped magnetic core, wherein the thick black line shown in FIG.3B-FIG. 3D is an insulating layer exposed between the turns of the metalwinding, so is the thick black lines shown in the following figures.

Specifically, the first wiring layer, the first insulating layer, andthe second wiring layer are sequentially disposed from the outside tothe inside on the magnetic core. As shown in FIG. 3B, the metal winding32 is formed in the second wiring layer by e.g. an etching process or acopper foil winding process such that the second winding 32 winds aroundthe four magnetic columns of the magnetic core 31 in a foil structure.After the second winding 32 in the second wiring layer is formedcovering the magnetic core 31, a first insulating layer is disposedoutside the second wiring layer, and then a first wiring layer isdisposed outside the first insulating layer, wherein the firstinsulating layer is used for the insulation between the first wiringlayer and the second wiring layer. And therefore, the second wiringlayer is at least partially covered by the first insulating layer and atleast partially covered by the first wiring layer. As shown in FIG. 3C,the first metal winding 33 e.g. a one-turn winding is formed in thefirst wiring layer and winds around all the magnetic columns of themagnetic core 31 in a foil structure. The first winding 33 wraps aroundthe magnetic core 31 and also at least partially covers the secondwinding 32. Therefore, the second winding is also at least partiallycovered by the first winding, and the first insulating layer is also atleast partially covered by the first winding. The cover described in thepresent disclosure may be contact cover or non-contact cover, such asprojection cover. As described above, the “cover” in “the firstinsulating layer is at least partially covered by the first metalwinding” means contact cover. The “cover” in “the second metal windingis at least partially covered by the first insulating layer” also refersto contact cover. The “cover” in “the second metal winding is at leastpartially covered by the first metal winding” means non-contact cover,that is, projection cover.

Specifically, in an embodiment, an initial insulating layer may beselectively attached to the surface of the magnetic core by spraying ordeposition, and the initial insulating layer has the function ofenhancing the bonding force and protecting the magnetic core, but thepresent disclosure is not limited to this, alternatively, the initialinsulating layer may be or may not be provided. A second wiring layermay be a metal layer e.g. a copper layer and disposed on the core byelectroplating or electroless plating process; and then a metalprotective layer, such as a tin layer or a gold layer, is disposed onthe surface of the second wiring layer by electroplating or electrolessplating; then the metal protective layer is patterned by a writingprocess to expose a portion of the second wiring layer which needs to beetched; and then the portion of the second wiring layer which needs tobe etched are etched under the protection of the metal protective layerto form a second metal winding; finally, the protective layer is removedand the second winding, e.g. the primary winding P comes into being asFIG. 3B shows. Then, the first insulating layer is selectively attachedto the second metal winding by spraying or deposition, and the firstinsulating layer has the function of enhancing the bonding force andprotecting the magnetic core. And a similar process is adopted. A firstwiring layer is provided on the surface by plating or electrolessplating, the first wiring layer may be a copper layer; then a metalprotective layer is electroplated or electroless plated on the surfaceof the first wiring layer, such as a tin layer or a gold layer; and thenthe metal protective layer is patterned by a writing process to expose aportion of the first wiring layer which needs to be etched; and then theportion of the first wiring layer are etched under the protection of themetal protective layer to form a first metal winding; finally, theprotective layer is removed to expose the first metal winding, e.g. thesecondary winding S2. However, the present disclosure is not limitedthereto, and other winding forming processes are also applicable. Forexample, the first and second winding may be the copper foils made bye.g. a punching or cut process to wind around the columns of the core.Or the first winding may be the copper foil winding and the secondwinding may be the litz wire winding winded around the columns of thecore.

In this embodiment, it can be seen that the second winding 32 is aspiral winding with plural turns surrounding all the columns of the

-shaped (or hollow-square shaped) magnetic core. The first winding 33has one turn and also wraps all the magnetic columns of the

-shaped magnetic core. As a matter of fact, the second winding 32 maywind some columns of the core, e.g. one or two columns of the core, evena part of one magnetic column of the core. So does the first winding 33.As shown in FIG. 3C, a gap splits the winding 33 and forms two ends 331,332 of the winding on the bottom surface of the magnetic core byetching, cutting process etc.

Further, in conjunction with FIG. 3B to FIG. 3E, in this embodiment thesecond metal winding 32 also has a first end and a second end, which arecovered by an insulating layer and the first winding 33 and connected tothe third output pin P1 and the fourth output pin P2 (shown in FIG. 3D)by a first connector e.g. a via and a second connector e.g. a via (notshown) respectively for electrical connection with an external circuit.And both the first connector and the second connector just pass throughthe first insulating layer. Thus, the length of the connectors is veryshort, and the loss the connectors are small. Generally, there aremultiple first and second connectors distributed on the correspondingpads. Then the current distribution is more even. The first metalwinding 33 is, for example, a secondary winding of the transformer, andthe second metal winding 32 is, for example, a primary winding of thetransformer. And in this embodiment, the two output pins P1 and P2 areboth the surface-mounted pins. Actually, they may be other types ofpins, such as, DIP pins, pins made by coils etc.

The transformer module is connected to an external circuit (such as aswitch module) by the first output pin V0, the second output pin D2, thethird output pin P1, and the fourth output pin P2, wherein in thisembodiment these pins are all surface-mounted pins and they may be othertypes of pins, such as DIP pins etc. For example, if the first windingis the copper foil made by punching or cut process, then the pins mayalso be made by the copper foil. That is to say, the pins and the firstwinding are integrated. The first surface-mounted pin V0, the secondsurface-mounted pin D2, the third surface-mounted pin P1, and the fourthsurface-mounted pin P2 are all located on the first side (for example,the bottom surface) of the transformer module. In this embodiment, thefirst side of the transformer module is the outer surface of the firstwiring layer. The first side may also be a surface in parallel with theouter surface of the first wiring layer, wherein the surface in parallelwith the outer surface may be close to the outer surface and thedistance between two surfaces are small, for example, not more than 1mm, which facilitates external assembly and connection. However, thedisclosure is not limited thereto.

The first pin V0, the second pin D2, the third pin P1 or the fourth pinP2 may have various shapes, such as a square shape or a circle shape. Insome embodiments, the first pin V0, the second pin D2, the third pin P1or the fourth pin P2 may be surface-mounted pins. In FIG. 3D, D2 and V0may be big hollow square shape pads or circle shape pads without P1 andP2 pins, while P1 and P2 are small rectangular shape pads.

In some embodiments, in the above embodiment, the first surface-mountedpin V0, the second surface-mounted pin D2, the third surface-mounted pinP1, and the fourth surface-mounted pin P2 may be located on thedifferent sides of the transformer module, for example, V0 and D2 can belocated on the first side of the transformer module, while P1 and P2 canlocated on the second side of the transformer module, wherein the firstside and the second side are different sides.

In the prior art shown in FIG. 1 , for a multilayer PCB transformer, thewinding has different radii of different parts of the same layerwinding, so that the impedance of the inner ring of the same layerwinding is smaller than the impedance of the outer ring, so the currentdistribution on the same layer winding is not uniform, and the loss ofthe winding is correspondingly larger. And the windings in differentlayers are connected to each other through vias. But in the traditionalPCB process, the diameters of these vias are big, usually larger than150 microns. The distance between two vias is typically greater than 150microns for structure and pattern considerations. In this embodiment,since the traditional PCB board is no longer disposed, the first via andthe second via may be directly formed in the first insulating layer bylaser drilling or the like, so that the first via and the second viahave smaller diameter, which can increase the number of via and furtherreduce the impedance of via. However, the disclosure is not limitedthereto.

The vias may be hollow generally. However, by adjusting theelectroplating agent the vias may also be filled with metal, e.g. copperfor winding loss reduction.

Further, as described above, in a PCB winding structure, the windings indifferent layers may connect to each other through vias. Generally, suchvias are long and have large impedance, and the winding loss caused bythe vias is large. In this embodiment, since the insulating layer suchas the first insulating layer has a thickness less than 200 μm which ismuch smaller than the insulating layer of the PCB winding structure, thefirst via and/or the second via are short and the impedance is small, sothat the loss of the winding caused by the vias can be reduced greatly.

Further, in the prior art, the pins of the secondary winding of thetransformer of the multi-layer PCB structure can only be led out on thesurface of the PCB, and the pins of the secondary winding of the innerlayer can only be led to the surface of the PCB through the vias, thuscausing that the current is concentrated and the winding loss isexcessive. In some embodiments of the present disclosure, the metalwinding as the secondary side may be evenly foil winded around themagnetic core, and a plurality of sets of corresponding surface-mountedpins may be uniformly distributed on the first side of the magneticcore, thus the current is evenly distributed on the whole winding. Basedon this, the winding loss can be reduced.

Further, the power of the transformer module provided by someembodiments of the present disclosure is easy to expand, and all themagnetic column can be covered with a winding to improve the power ofthe transformer module. The magnetic module can be lengthened and thewinding can be widened to increase the power of the transformer module.

As described in this embodiment of this application, the transformerwinding is in a foil structure, the equivalent diameters of each part ofthe winding are similar, thus the equivalent impedances of each part aresimilar, thereby an almost even current distribution of the winding isachieved. The inner winding connects to the output pins by the connectorpassing through the insulation layer between the wiring layers thatinner winding and the outer winding lay on which reduces the length ofthe connector greatly when compared with the prior art in FIG. 2 . Sothe loss of the connector is reduced greatly. Furthermore, as shown inFIG. 3D, the connectors or the pinouts may be plurals and distributedwhich can further improve the even current distribution of the winding.So the loss of the winding reduces greatly.

As shown in FIG. 3C and FIG. 3D, the first metal winding is a copperfoil wound around the magnetic core in a foil structure continuously,the winding covers four magnetic core columns, and the two ends of thewinding are respectively connected to the two pins V0 and D2, these twopins are connected to external circuits such as switch devices, etc.,wherein the number of each of pins V0 and D2 is one, as shown in FIG.3D. The structure shown in FIG. 3F is slightly different from 3D. InFIG. 3F, the metal winding continuously winds on part of the magneticcolumns of the

-shaped core, such as three magnetic columns. The two ends of thewinding are still connected to the two pins V0 and D2, and the number ofeach of the pins V0 and D2 is also one. Taking FIG. 3F as an example,from the side of the transformer, a is the inner length of the winding,and b is the outer length of the winding. Therefore, it can beconsidered that the average length of the winding W=(a+b)/2, and d isthe average length of the pins on the winding, n is the ratio of the pinlength to the winding length, n=d/W. Since the windings are connected tothe external circuit through the pins, the length of d will affect theuniformity of the current distribution on the winding. For the averagelength of a certain winding, as d increases, the current distributionwill become more uniform and the winding loss will become smaller andsmaller. As shown in FIG. 3G, the abscissa in FIG. 3G is n, and theordinate P is the winding loss, as n increases, the correspondingwinding loss is greatly reduced. Preferably, when d ≥½ W, the windingloss is small and tends to be stable. In FIG. 3D, n=1, that is, thelength of the pin is almost equal to the average length of the winding,so the pin structure in FIG. 3D can make the current distribution on thewinding more uniform, and correspondingly the winding loss is smaller.In this application, the magnetic core is not limited to the

-shape, and is also applicable to the magnetic cores of the T-shape,UU-shape and UI-shape.

Similarly, for the plurality of pins of the secondary winding, as shownin FIG. 3H which is similar to FIG. 3F, both of them include a

-shaped magnetic core, and a continuous winding wound on three magneticcolumns. Different from FIG. 3F, the winding of FIG. 3H includes aplurality of first pins V0 and a plurality of second pins D2, that is,the numbers of the first pin V0 and the numbers of the second pin D2 areboth greater than or equal to 2. As shown in FIG. 3H, the total lengthof the pin includes three parameters: d1, d2, and d3, and the totallength of the pin is d=d1+d2+d3. In FIG. 3H, if V0 or D2 is only asingle pin, the length of the V0 or D2 pin is small, that is, the ratioof the length of the pin to the average length of the winding n isrelatively small, so that the corresponding winding loss is still notsmall. However, for a plurality of pins of V0 or D2, for example, threepins as shown in the figure, the length of the pin is greatly increased,and the ratio n of the length of the pin to the average length of thewinding becomes larger, which will cause current distribution on thewinding more even. It can be understood that the first pin V0 and thesecond pin D2 in the figure can be various shapes such as a square shapeor a circle shape, for example, when the pin is a circle shape, thelength of the pin can be the diameter of the circle. Furthermore, thedistribution of the plurality of first pins V0 and the plurality ofsecond pins D2 is more uniform, the current distribution in the windingis more uniform, and correspondingly, the winding loss is smaller. Ingeneral, preferably, when the total length d of the first pins V0 or thesecond pins D2 is greater than or equal to ½ of the winding length W,the winding loss is small and tends to be stable; the more the number ofthe first pins V0 or the second pins D2, the smaller the winding loss;the more uniform the distribution of the first pins V0 or the secondpins D2, the smaller the winding loss.

In the present embodiment of FIG. 3C-3D, only one schematic of thetransformer module in a foil structure is shown, that is, the winding inthe foil winding structure covers the four magnetic columns of themagnetic core. In fact, the winding in the foil winding structure cancover one magnetic column or a plurality of magnetic columns. Thisapplication does not limit this.

Further, the transformer module provided by some embodiments of thepresent disclosure is easy to expand, and all the magnetic columns canbe covered with a winding to improve the power of the transformermodule. The magnetic columns can be lengthened and the winding can bewidened to increase the power of the transformer module.

Embodiment 2

On the basis of embodiment 1, embodiment 2 of the present disclosurefurther provides a transformer module, wherein the magnetic core of thetransformer module further includes a second insulating layer and athird wiring layer beneath the second wiring layer, so the secondinsulating layer is at least partially covered by the second winding.

The transformer module further includes: a third winding on the thirdwiring layer and winds around the magnetic core in a foil structure,wherein the third winding is also at least partially covered by thesecond insulating layer; and a fifth surface-mounted pin which islocated on the first side of the transformer module for electricallyconnecting the covered third winding.

FIG. 4 shows another embodiment. Specifically, FIG. 4C shows atransformer with a primary winding P and center-tapped secondarywindings S1 and S2. The primary winding P has two ends a and b connectedto the pins P1 and P2. One secondary winding S1 has two ends f and dconnected to the pins D1 and V0 while the other secondary winding S2 hastwo ends c and e connected to the pins V0 and D2. S1 and S2 areconnected in series on the common end which connects to the pin V0. Theprimary winding P and center-tapped secondary windings S1 and S2 areconnected to an external circuit through ends a, b, c, d, e, and f. FIG.4B is the bottom view of the corresponding transformer of FIG. 4C. FIG.4A is the bottom view of the transformer with winding S1. Referring toFIGS. 4A-4C, unlike the embodiment shown in FIGS. 3A-3E, the thirdwiring layer is further added in this embodiment, that is, the firstwiring layer, the first insulating layer, the second wiring layer, thesecond insulating layer and the third wiring layer are respectivelydisposed from the outside to the inside on the magnetic core. The firstwiring layer, the second wiring layer, and the third wiring layer arerespectively used to form the first metal winding S2, the second metalwinding P, and the third metal winding S1 which forms a “sandwich”transformer structure S1-P-S2. Assuming that the third winding 34 has,for example, one turn, as shown in FIG. 4A, and the third winding 34wraps four magnetic columns of the

-shaped magnetic core, and forms two ends 341 and 342 on the bottom sideof the magnetic core by the process e.g. etching, cutting, or the likeetc. FIG. 19 is a perspective view of a transformer module of FIG. 4Aaccording to an embodiment of the present disclosure. In FIG. 19 , thedimension of the winding parallel to the longitudinal direction of themagnetic column is W, which is represented by a rectangle-like arrow;and the thickness of the winding which is the dimension of the windingvertical to the magnetic column of the magnetic core is H, which is alsoshown in FIG. 17 . It is noted that only the thickness of the firstwinding is shown in FIG. 17 and the thickness of the second winding andthe third winding is omitted for simplification.

FIG. 4B shows the bottom view of the transformer with the secondinsulating layer, the second wiring layer, the first insulating layer,the first wiring layer, winding outside the third wiring layer insequence. So the third winding is at least partially covered by thesecond insulating layer. The two ends of the third winding 34 include afirst end 341 connected to the fifth pin D1 of the outermost layerthrough a third connector e.g. a via (not shown) for the electricalconnection to an external circuit wherein pin D1 may locate on the firstside (for example, the bottom surface). The second end 342 of the thirdwinding 34 is usually connected to one end of the first wiring layerwinding, and is connected to the first surface-mounted pin V0 throughthe fourth connector e.g. a via (not shown), which is not limited in thepresent disclosure. That is to say, the two ends 341, 342 pass throughthe second insulating layer, the second wiring layer and the firstinsulating layer. The first winding and the second winding are connectedto the external pin in the same manner as the foregoing embodiment, andthe first winding connects the first surface-mounted pin V0 and thesecond surface-mounted pin D2, and the second winding connects the thirdsurface-mounted pin P1 and the fourth surface-mounted pin P2.

Specifically, a base insulating layer may be selectively attached to thesurface of the magnetic core by spraying or deposition, which is usedfor insulation, strengthening the bonding force, and protecting themagnetic core, but the disclosure is not limited to this, and the baseinsulating layer may not be disposed. And a third wiring layer, forexample a copper layer, may be disposed on the surface of the magneticcore or the base insulating layer by electroplating or electrolessplating; and then a metal protective layer, such as a tin layer or agold layer, may be disposed on the surface of the third wiring layer byelectroplating or electroless plating; then the metal protective layeris patterned by a writing process to expose a portion of the thirdwiring layer to be etched; and then patterns of the third wiring layerare etched under the protection of the protective layer to form a thirdwinding; finally, the protective layer is removed to expose the thirdwinding, that is, the secondary winding S1. Then, the second insulatinglayer is attached to the third metal winding by spraying or deposition,and then a second wiring layer, e.g. a copper layer is provided on thesecond insulating layer by electroplating or electroless plating; then ametal protective layer, such as a tin layer or a gold layer, iselectroplated or electrolessly plated on the surface of the secondwiring layer; and then the metal protective layer is patterned by awriting process to expose a portion of the second wiring layer to beetched; and then patterns of the second wiring layer are etched underthe protection of the metal protective layer to form a second winding;finally, the protective layer is removed to expose the second metalwinding, that is, as the primary winding P. Then, the first insulatinglayer is attached to the second metal winding by spraying or deposition,and then a first wiring layer, e.g. a copper layer is provided on thefirst insulating layer by electroplating or electroless plating; then ametal protective layer, such as a tin layer or a gold layer, iselectroplated or electrolessly plated on the surface of the first wiringlayer; and then the metal protective layer is pattern defined by awriting process to expose a portion of the first wiring layer to beetched; and then patterns of the first wiring layer are etched under theprotection of the metal protective layer to form a first winding;finally, the protective layer is removed to expose the first winding,that is, as the secondary winding S2. However, the disclosure is notlimited thereto, and other winding forming processes are alsoapplicable.

An optional method, as shown in FIG. 4B, the fifth surface-mounted pinsD1 have plural pins, locating between the first surface-mounted pin V0and the second surface-mounted pin D2. Further, the secondsurface-mounted pin D2 further includes a plurality of teeth 41, whichare alternately arranged with the plurality of fifth surface-mounted D1pins. In an embodiment, the plurality of teeth 41 are evenly alternatelyarranged with the plurality of fifth surface-mounted pins D1. Theplurality of fifth surface-mounted pins and plurality of secondsurface-mounted pins are used to connect multiple sets of switches andhelp to reduce impedance and improve integration. The more evendistribution the pins D1, D2 has, the more even current distribution ofcurrent the transformer has. And the smaller impedance the transformerhas. In an embodiment, the surface-mounted pins may be columnar orspherical, etc., and the disclosure is not limited thereto.

Alternatively, FIG. 5 is a bottom view of another transformer moduleprovided by an embodiment of the present disclosure. In contrast to FIG.4 , the fifth pin D1 is located between the first pin V0 and the secondpin D2. The magnetic core may include a through hole 61, the fifth pinD1 partially surrounds the through hole 61, for example, the fifth pinD1 has a C-shape. From the bottom view of the transformer module, thefirst pin V0 is a hollow square shaped pin surrounding the through hole61, and the second surface-mounted pin D2 is C-shaped partiallysurrounding the through hole 61. However, the present disclosure is notlimited thereto. By adjusting the positions of the third pin P1 and thefourth pin P2, the first, second, and fifth pins may also form othershapes such as the

-shape (hollow square shape) surrounding the through hole. Shapes suchas C-shape, hollow square-shape can increase the connection strengthwith external modules and are suitable for connecting multiple modules.

Embodiment 3

FIG. 6A and FIG. 6B are schematic diagrams of a power module provided byan embodiment of the present disclosure with corresponding ends markingon them. FIG. 6C and FIG. 6D are respectively cross-sectional views ofpower modules of FIG. 6A and FIG. 6B. With reference to FIG. 6A to FIG.6D, the power module includes: a transformer module 71 as in variousembodiments of the present disclosure; and a switch module 72, theswitch module 72 and the first side (for example, the bottom surfacehaving a pin) of the transformer module 71 are in contact andelectrically connected to the first pin V0 and the second pin D2.

As shown in FIGS. 6A and 6C, the power switch 73 is electrical connectedto the first pin V0. FIG. 6B shows that the switch module may alsoinclude at least one full bridge circuit formed by four power switches(such as MOSFETs), and the full bridge circuit is electrically connectedto the first pin V0 and the second pin D2. In an embodiment, the switchmodule 72 may include a board 74 and at least one power switch 73 whichis embedded or molded in the board 74 as shown in FIG. 6C and FIG. 6D.And the power switches may be disposed on the board 74 (not shown).According to the practical application of the circuit topology,different types of power switches can be selectively electricallyconnected to the first pin and/or the second pin, the present disclosureis not limited to this, and the power switch can also be connected toother pins. Take FIG. 6A as an example, SR 73 may be connected betweenthe first pin V0 and the output pin GND or between the second pin D2 andthe output pin VOUT according to different topology. Each power switchshown in the figures can be connected in parallel by multiple powerswitches according to the output power of the actual transformer. Asshown in FIG. 6C and FIG. 6D, the power switch may be located on thelower surface of the transformer module, or the power switch may also belocated on the upper surface of the transformer module, which is notlimited in the present disclosure.

Wherein, the power switch can be a diode, a Metal-Oxide-SemiconductorField-Effect Transistor (MOSFET), an Insulated Gate Bipolar Transistor(IGBT) and the like.

Specifically, the bare die of one or more parallel power switches SR canbe directly integrated into a board by an embedded process to form theswitch module, but the disclosure is not limited thereto. The powerswitch can be placed just below the pins of the transformer module foreasy connection to the pins. Referring to FIG. 3C, in this embodiment,although the numbers of the first pin V0 and the second pin D2 are bothone, if the size of the power switch or the size of the externalconnection pin of the switch module is smaller than the size of thetransformer module, a plurality of parallel SRs can be connected to thepins, and the SRs can be evenly distributed or unevenly distributed onthe pins. The embodiment shown in FIG. 5 can also be similarly set.Referring to FIG. 4B, in this embodiment, the plurality of fifth pins D1and the teeth of the plurality of second pins D2 can be used to connecta plurality of power switches. FIG. 6E is a bottom view of the switchmodule provided by an embodiment of the present disclosure. As shown inFIG. 6E, the lower surface of the board may form an output pin, such asVOUT, GND, and the like. Then the corresponding transformer module iswelded to the board to form a power module, as shown in FIGS. 6C and 6D.

Alternatively, one or more parallel SRs are firstly welded to thesurface of the board, then the switch module is formed by a moldingprocess, the other surface of the board forms a pad corresponding to thetransformer module, and the transformer module is welded on thecorresponding surface of the board to form the power module.

Further, the power module further includes a capacitor module disposedon the board and disposed adjacent to the transformer module. As shownin FIG. 6A and the like, the capacitor module can be electricallyconnected to the second pin D2. In another embodiment, as shown in FIG.7 , the capacitor module can be electrically connected to the first pinV0, and the disclosure is not limited thereto. The power module mayfurther include an LLC power unit, a controller, etc., so that the powermodule is used as an LLC converter. Specifically, FIG. 6F is across-sectional view of a power module provided by an embodiment of thepresent disclosure, as shown in FIG. 6F, Co is the output capacitor. InFIG. 6F, Co is placed on the switch module and beside the transformer.When the core of the transformer is a square or circle shape, Co may beplace inside the window of the core, e.g. the hole of the core in FIG.3A. Furthermore, Co may be placed on the board of the switch module oreven embedded inside the board of the switch module.

It should be noted that the above power module is not limited to the LLCconverter, and is also applicable to any circuit including a transformermodule, such as a flyback converter, a full bridge circuit, and thelike.

Embodiment 4

On the basis of the embodiment 3, the present disclosure furtherprovides a power module, wherein the power module includes a transformermodule similar to the embodiment 2, and the second insulating layer andthe third wiring layer are sequentially disposed on the magnetic core,and the second insulating layer is at least partially covered by thesecond metal winding. The transformer module further includes: a thirdmetal winding formed in the third wiring layer winded around themagnetic core in a foil structure, wherein the third winding is at leastpartially covered by the second insulating layer; and a fifth pin, thefifth pin is located on a first side (e.g., a bottom surface) of thetransformer module, and a first end of the third winding is electricallyconnected to the fifth pin D1 through the third connector, such as via,the second end of the third winding is electrically connected to thefirst pin V0, and the rest is not described herein.

FIG. 7 is an electrical schematic diagram of a power module providedwith plurality of ends marking on it by an embodiment of the presentdisclosure. As shown in FIG. 7 , the secondary windings S1 and S2 of thecenter-tapped transformer are connected to a first power switch, asecond power switch and a cap respectively. And after the transformermodule and the switch module are stacked, the switch module is furtherelectrically connected to the fifth pin.

Further, as shown in FIG. 7 , the power module further includes a firstpower switch (SR) and a second power switch (SR), wherein the first endof the first power switch is electrically connected to the second pinD2, the first end of the second power switch is electrically connectedto the fifth pin D1, and the second end of the first SR and the secondend of the second SR are electrically connected, but the disclosure isnot limited thereto, and each of the illustrated power switches mayactually be equivalently connected in parallel by a plurality of powerswitches depending on the power level of the device.

Further, the power module further includes a capacitor module, forexample, as an LC resonant capacitor or an output capacitor, and thepresent disclosure is not limited thereto. Further, the capacitor moduleis disposed on the board and adjacent to the transformer module, and thecapacitor module is electrically connected to the first pin V0, as shownin FIG. 6F, and Co is an output capacitor. In some other embodiments,the capacitor may also be located adjacent to the same side of theswitch device SR on the carrier board; or the capacitor may also beembedded in the carrier board; or the capacitor may be placed in thewindow of the transformer, when the transformer core of FIG. 6F is a

-shape, etc.; even if the capacitor is placed on the upper surface ofthe magnetic core, the power switch SR is placed on the lower surface ofthe magnetic core. Wherein, the power module may further include an LLCprimary power unit, a controller, etc., such that the power modulefunctions as an LLC converter.

It should be noted that the above power module is not limited to the LLCconverter, and is also applicable to any circuit including a transformermodule, such as a flyback converter, a full bridge circuit, and thelike.

It can be seen that the power module is easy to be modular produced.First, multiple power switches SRs are integrated on one board to formmultiple switch modules. Then, multiple transformer modules are surfacemounted to the corresponding switch modules, thus multiple power moduleswith a common board come into being, wherein each power module has oneswitch module and one transformer module stacked on the switch module.And finally separate the power modules by e.g. cutting process, so thatindependent multiple power modules can be produced at one time, but thedisclosure is not limited thereto.

Further, the power switches are directly connected to the plurality ofoutput Pins of the transformer module, and the connection loss is small;the primary and secondary circuits of the transformer module aredirectly coupled to each other, the AC impedance of the windings issmall, and the AC loss is small, but the present disclosure is notlimited to this.

In some embodiments including embodiment 1 to embodiment 4, thecorrespondence of the surface-mounted pins is (but not limited to):

-   -   the first pin corresponds to V0, and it can be seen from FIGS.        3E, 4C, 6A, 6B, and 7 , it can correspond to the first end of        the first metal winding S2 or the second end of the third metal        winding S1, etc. According to different topologies, the first        pin may be used as the output pin of the module in FIG. 7 or it        may be used to connect the switch as shown in FIGS. 6A and 6B.    -   the second pin corresponds to D2, and it can be seen from FIGS.        3E, 4C, 6A, 6B, and 7 , it can correspond to the second end of        the first metal winding S2. According to different topologies,        the first pin may be used for connection with the power switch,        such as shown in FIG. 6B and FIG. 7 , or it may be used for        connection with the secondary grounding, as shown in FIG. 6A.    -   the third pin corresponds to P1, and the fourth pin corresponds        to P2, and they can respectively correspond to two ends of the        second metal winding P.    -   the fifth pin corresponds to D1, it can be seen from the FIGS.        4C, and 7 that it can correspond to the first end of the third        metal winding (which may be used as the secondary winding S1).        and can be used for the connection with the power switch.

However, in some other embodiments of the present disclosure, such as inthe embodiment 5 to the embodiment 7, for the convenience ofdescription, the electrical connection points corresponding to the pinsare not the same as the corresponding electrical connection points inthe foregoing embodiments, the present disclosure is not limited tothis.

Embodiment 5

In the above embodiments, respective windings of the transformer may belocated in the same wiring layer, but the disclosure is not limitedthereto. FIG. 8 is a cross-sectional view of the transformer module ofFIG. 5 taken along line AA′, from which it can be seen that the windingsare respectively located in the first, second, and third wiring layers,wherein the first, second and third wiring layers are arranged in orderfrom the outside to the inside, and the first insulating layer (FIL) isbetween the first wiring layer and the second wiring layer, and thesecond insulating layer (SIL) is between the second wiring and the thirdwiring layer. In FIG. 8 , the connecting via between the first end ofthe winding S1 in the third wiring layer and the second pin D1 isrepresented by a dash line while the via between the second end of thewinding S1 and V0 is represented by a shadow area, because the viaconnecting the first end of the winding and D1 is not in the crosssection along AA′. And FIG. 8 shows that one winding is substantially onone wiring layer. Similarly, FIG. 17 is a cross-sectional view of thetransformer module taken alone line BB′ shown in FIG. 5 according to anembodiment of the present disclosure, and FIG. 18 is a cross-sectionalview of the transformer module taken alone line CC′ shown in FIG. 5according to an embodiment of the present disclosure. In FIG. 17 , theconnecting via FC between the first end of the winding P in the secondwiring layer and the third pin P1 is represented by shadow area, becausethe via FC connecting the first end of the winding P and P1 is in thecross section along BB′. In FIG. 18 , the connecting via SC between thesecond end of the winding P and the fourth pin P2 is represented byshadow area, because the via SC connecting the second end of the windingP and P2 is in the cross section along CC′.

In practice, the windings can also be placed in a staggered manner, thatis to say that different parts of the same winding can be located indifferent wiring layers, for example in two wiring layers. Across-sectional view of such a winding arrangement is shown in FIGS. 9Aand 9B. As shown in FIGS. 9A and 9B, 191 is a magnetic core; a firstmetal winding wound around the magnetic core 191 in a foil structureincludes a first winding segment 1922 formed in the first wiring layerand a second winding segment 1921 formed in the second wiring layer, thefirst end of the first winding segment is electrically connected to thefirst end of the second winding segment through a via, and the secondend of the first winding segment is electrically connected to the firstpin V0 through a via, the second end of the second winding segment isconnected to the second pin D1; the second metal winding also windsaround the magnetic core 191 in a foil structure, and includes a thirdwinding segment 1941 disposed on the first wiring layer and a fourthwinding segment 1942 formed in the second wiring layer, the first end ofthe third winding segment is connected to the first end of the fourthwinding segment through a via, and the second end of the fourth windingsegment forms a third pin D2. As shown in the figure, the second end ofthe third winding segment is connected to the first pin V0 through avia. Thus, the first and second windings form a connection structure ofthe transformer secondary windings S1, S2 as shown in FIG. 7 . Thewinding P of the transformer in FIG. 7 is the third metal winding 193 onthe third wiring layer in FIGS. 9A-9B, and the third wiring layer andthe second insulating layer may be sequentially located between thefirst insulating layer FIL and the second wiring layer. The secondarywindings S1, S2 in FIG. 7 are arranged by a staggered arrangementmethod, which greatly improves the symmetry between the two windingscompared to the arrangement mode of the same winding being located inthe same winding layer as shown in the FIG. 8 , and the current sharingeffect of the current flowing through the first SR, the second SR duringthe working process of the circuit is significantly improved. Inaddition to the winding of FIG. 7 , this way of staggered layerarrangement can be used in the winding of FIG. 6 , that is to say, andthe first and second metal windings, such as winding P and winding S2 inFIG. 6 may also become the windings lay on different wiring layer justas the windings shown in FIG. 9A, 9B.

The design of the pins can be similar to other embodiments in thepresent disclosure, for example, there are a plurality of third pins D2,the second pin D1 includes a plurality of teeth, and the plurality ofteeth and the plurality of third pins D2 are alternately arranged; orthe numbers of the second and third pins are both plural, and theplurality of second pins and the plurality of third pins are alternatelyarranged and so on, as shown in FIG. 9D. FIG. 9C is a bottom view of thetransformer in an embodiment of the present application, including afirst pin V0, a second pin D1, and a third pin D2, wherein the first pinV0 is located between the second pin D1 and the third pin D2, the lengthof each pin is almost equal to the average length of the winding; thefirst, second and third pins can be either a

-shape or a plurality of pins being distributed on a part of thewindings as shown in FIG. 9D. And the plurality of pins aresymmetrically arranged, the present application is not limited to this.

The corresponding power module may include a switch module, and theswitch module is in contact with the first side of the transformermodule. The switch module can include a board and at least one powerswitch. Similar to FIG. 7 , the switch module includes a plurality offirst SRs and a plurality of second SRs; a first end of the first SR isconnected to the first pin D1, and a first end of the second SR isconnected to the third pin D2, a second end of the first SR iselectrically connected to a second end of the second SR. According todifferent pins of the transformer, the plurality of first SRs (i.e., SR1in FIG. 9E) and the plurality of second SRs (i.e., SR2 in 9E) can beseparated into two rows as shown in FIG. 9E. FIG. 9E is a schematicillustration of a portion of the transformer and the switching elementsdisposed thereon, taken along the dashed line in FIG. 9C. The portion ofthe transformer module includes three pins D1, D2 and V0. The pin V0 islocated between D1 and D2. There is a switch module on the transformermodule, and the switch module includes a plurality of SR1 s and aplurality of SR2 s. The plurality of SR1 s and the plurality of SR2 sare separated into two rows. The switch module is in contact with oneside of the transformer. In addition, the power switches can also bearranged in the same row, wherein SR1 and SR2 are arranged in astaggered manner, and the present application is not limited thereto. Ofcourse, the switch module can also include a carrier board, and theswitch can be placed on the carrier board or embedded in the carrierboard.

Further, the power module may further include a capacitor moduledisposed on the board and disposed adjacent to the transformer module,and the capacitor module is electrically connected to the first pin orthe second pin. The present disclosure is not limited to this. Forexample, the capacitor may be located below the carrier board, as shownin FIG. 9F, the capacitor Co is located below the power switch. And thecapacitor Co can also be buried in the carrier board or placed on theother side of the transformer opposite the switch module, such as theupper side of the transformer module in FIG. 9F; And the capacitor Cocan also be placed in the window of the magnetic core. In short, thelocation of the capacitor module is varied.

In the circuit diagram shown, for example, in FIG. 7 , if the secondarywindings S1 and/or S2 are separately segment formed to lead theconnection ends on different sides of the transformer module, thepositions of the first SR and/or the second SR are not necessary limitedto the bottom surface of the transformer module, but are electricallyconnected in series in the corresponding metal windings by pins S1′, D1,and/or S2′, D2 in FIGS. 11A and 11B, devices may be flexibly disposed onmultiple surfaces, which is beneficial to optimize the spatialdistribution. This portion will be further described in Embodiments 6 to8.

Embodiment 6

In the previously described embodiment, the windings of the transformerare formed by electroplating, and the pins are led out through viaholes, but the disclosure is not limited thereto. As shown in FIG. 8 ,the winding of the transformer is a winding layer formed byelectroplating or electroless plating, and the pins D1 and V0 areconnected to the inner layer winding through via holes, but thedisclosure is not limited thereto.

In fact, the winding of the transformer can also be formed by metal foilin a foil structure, such as copper foil. FIG. 10A is a cross-sectionalview of a transformer in an embodiment of the present application. Asdescribed in the embodiment 2, the transformer module includes a firstmetal winding 1104, a second metal winding 1103, and a third metalwinding 1102 from the outside to the inside. The initial insulatinglayer is located between the third metal winding and the magnetic core,and the second insulating layer is located between the third and secondmetal windings, and the first insulating layer is located between thesecond and first metal windings. Wherein the second metal winding 1103can be used as the primary winding P, the third wiring layer metalwinding 1102 can be used as the secondary winding S1, and the firstwiring layer metal winding 1104 can be used as the secondary winding S2to form the “sandwich” structure of the secondary windings sandwichingthe primary winding. The third metal winding 1102 is a whole copperlayer covering the magnetic core column 1101, so the magnetic corecolumn 1101 is at least partially covered by the initial insulatinglayer and the third metal winding 1102, and similarly, the third metalwinding 1102 is also at least partially covered by the second insulatinglayer and a second metal winding 1103, and the second metal winding 1103is at least partially covered by the first insulating layer and thefirst metal winding 1104.

Similar to the embodiment 2, the third metal winding 1102 includes twoends, which are a first end and a second end, wherein the first end isconnected to the fifth pin of the outermost layer, for example, the pinD1, for electrical connection to the outside. The second end of thethird metal winding 1102 is typically connected to one end of the firstmetal winding 1104 and is commonly connected to the first pin of theoutermost layer, such as pin V0. The first and second ends of the thirdwinding pass through the second insulating layer, the second windinglayer, the first insulating layer and the first winding layer. Differentfrom the embodiment 2, the first end of the third metal winding 1102 andthe second end of the third metal winding 1102 are not led out by viaholes. FIG. 10B-FIG. 10F illustrate one approach of making metal windingusing one-piece metal foil.

First, a whole piece of metal foil, such as a copper foil, is cut into astructure as shown in FIG. 10B (i.e., an expansion view of the thirdmetal winding). A “

”-shape structure as shown in the figure is cut on the two parallelsides of the copper foil, and the structure is used to form the pins1001, 1002 of the winding; then, the copper foil is folded according tothe dot dash lines in the figure. The folded shape is as shown in FIG.10C. Then, a long strip of copper foil as the second metal winding ofthe transformer is used to wind around the surface of the third metalwinding, and the respective erected pins 1001, 1002 of the third metalwinding are avoided during the winding process, as shown in FIG. 10D;finally, a first metal winding is fabricated using a process similar tothat of fabricating the third metal winding. A whole piece of copperfoil is cut and folded into a first metal winding as shown in FIG. 10E,and holes 1003 corresponding to the pins 1001, 1002 of the third metalwinding are cut at one end of the first metal winding to let the pins ofthe third metal winding protrude from the holes (in the figure, thereare two holes 1003 for the pins 1001, 1002 passing through, in fact, thetwo holes can be opened into one hole); finally, an insulation treatmentis performed on the pin of the first end of the third metal winding, andthen is bended and then lays on the surface of the first metal windingto form a fifth pin D1, the pin of the second end of the third wiringlayer metal winding is bended and then lays on the surface of the firstwiring layer metal winding for connecting to form a first pin V0, asshown in FIG. 10F to FIG. 10G.

In some embodiments, there may be a plurality of first, fifth, andsecond pins, and the plurality of first pins V0 are located between thefifth pins D1 and the second pins D2, and the first, second, and fifthpins are separately arranged in a row, as shown in FIG. 10G, and theapplication is not limited thereto.

Taking the insulation of the third metal winding 1102 as an example. Theinsulation requirement of the third metal winding includes an initialinsulating layer on the inner side and a second insulating layer on theouter side thereof. The initial insulating layer is used for insulationfrom the magnetic core column 1101, and the second insulating layer isused for insulation from the second metal winding 1103. The thicknessrequirement of the insulating layer depends on the interlayer withstandvoltage and the interlayer distributed capacitance. For example, in thiscase, the thickness of the insulating layer is required to be 70 μm. Inaddition, the insulating layer shall be windable, to avoid peeling fromthe metal layer during bending.

In response to these requirements, and how to effectively processinsulating layers between different metal wiring layers and between awiring layer and a magnetic core column, the present applicationprovides a new method of manufacturing an insulating layer. In the firststep, a surface roughening treatment is performed on the cut metalcopper, such as the third metal winding shown in FIG. includingmechanical grinding or chemical roughening and browning, in which brownoxidation treatment is optimal. The purpose of surface roughening is toincrease the contact surface area between the metal layer and theinsulating material, thereby increasing the adhesion of the insulatingmaterial, and ensuring that delamination and peeling between the metallayer and the insulating material do not occur during subsequentbending. In the second step, the base insulating layer 1006 by the firstinsulating process is formed on the metal layer 1102 after the surfaceroughening, as shown in FIG. 10B-1 . Insulation modes includeelectro-deposition, spraying or printing etc. Among them, theelectro-deposition mode is preferred, which has the lowest requirementon the shape of the metal layer, and is more reliable for the insulationof some parts that are difficult to process, such as the corners of themetal layer, and the adhesion performance is also better. For example,the electro-deposition can be acrylic electric coating, which iscomposed of polyacrylic resin and polyurethane hardener. The portion1007 where the connecters and pins are required can be avoided bycovering and shielding in advance. In the third step, the additionalinsulating layer 1006 by the second insulating process is formed afterthe base insulating layer, as shown in FIG. 10B-2 . The thickness of theinsulating layer that can be made by the mode of electro-deposition isrelatively limited, and typically, the thickness is between 0.1 and 30μm. Therefore, when the thickness of the insulating layer is required tobe greater than 30 μm, an additional insulating layer may be required.The additional insulating layer may be formed by, for example, providingan insulating glue 1008, as shown in FIG. 10B-2 . Wherein, theadditional insulating layer is not limited to insulating glue, and mayalso be fabricated by a photoresist film, local dispensing, and thelike. In order to avoid cracking of the insulating layer while bendingthe metal layer, partial insulating layer may be performed as shown inFIG. and FIG. 10B-3 . FIG. 10B-2 is a schematic cross-sectional view ofthe metal layer before being bent, and FIG. 10B-3 is a schematiccross-sectional view of the metal layer after being bent. As shown inthe FIG. 10B-3 , there is no insulating material in the corner portionthat need to be bent. The second insulation processing increases thetotal thickness of the insulating layer. Wherein, this step is notessential. In the case where the thickness requirement is not high, thebase insulating layer may meet the requirements. Finally, in anembodiment, an adhesive layer may be coated after the insulating layerto achieve bonding and fixing between the plurality of metal wiringlayers.

The manufacturing process of a metal winding is summarized as shown inFIG. 10B-4 . Step S1, cutting a metal copper foil to form the connectorand the pin; step S1.1: roughening the surface of at least one of thefirst mental copper foil and the second metal copper foil; step S2.1: afirst insulation processing is performed on the surface of the at leastone of the first metal copper foil and the second metal copper foil toform an inner base insulating layer; step S2.2: a second insulationprocessing is performed on the surface of inner base insulating layer ofthe metal copper foil to form an outer additional insulating layer; stepS2.3: coating an adhesive layer on the surface of at least one of thefirst metal copper foil and the second metal copper foil; step S3:bending the first metal copper foil to form a first metal winding tocover on the magnetic core. Step S4: the second metal copper foil is atleast partially covered on the surface of the first metal winding toform the second metal winding, and the pins of the first metal windingpass through the second metal winding. Step S5: cutting the third metalcopper foil to form through hole or gap, and bending the third metalcopper foil to at least partially cover the second metal winding to forma third metal winding, and the pins of the first metal winding passthrough the through hole or gap.

Wherein, step S1.1, step S2.2, and step S2.3 are all optional steps. Itshould be noted that the present application does not limit the orderbefore the foregoing steps. For example, step S2.1 and step S2.2 may beperformed before step S1, or may be performed after step S1. In someembodiments, the second metal copper foil in step S4 may be a long stripcopper foil, which is wound on the surface of the first metal winding asthe second metal winding, and forming a through hole or a gap during thewinding process to let the pins of the first metal winding pass through.

The corresponding power module can be referred to the power module inembodiment 5, and details are not described herein again.

In the circuit diagram shown, for example, in FIG. 7 , if the secondarywindings S1 and/or S2 are separately segmented to lead out theconnection ends on different sides of the transformer module, thepositions of the first SR and/or the second SR are not necessarilylimited to the bottom surface of the transformer module, but they areelectrically connected in series in the corresponding metal windings bythe pins S1′, D1, and/or S2′, D2 in FIG. 12A and FIG. 12B, which can beflexibly arranged on multiple surfaces. It is beneficial to optimize thespatial distribution. This section will be further described inembodiment 7 to embodiment 9.

Embodiment 7

FIG. 11A and FIG. 11B are respectively structural schematic diagrams ofthe transformer module provided by an embodiment of the presentdisclosure. FIG. 12A is a cross-sectional view of the transformer moduleprovided by an embodiment of the present disclosure taken along the lineAB shown in FIG. 11A. FIG. 12B is a cross-sectional view of atransformer module provided by an embodiment of the present disclosuretaken along the line AB of FIG. 11B, and the broken lines in FIG. 12Aand FIG. 12B indicate the omitted portion. Specifically, with referenceto FIG. 11A and FIG. 12A, the transformer module includes:

-   -   a magnetic core 91, the magnetic core 91 is provided with a        first wiring layer, a first insulating layer, a second wiring        layer, a second insulating layer and a third wiring layer in        order from the inside to the outside; and    -   a first metal winding winds around the magnetic core 91 in a        foil structure, and includes a first winding segment 922 formed        in the first wiring layer and a second winding segment 921        formed in the second wiring layer, the first end of the first        winding segment 922 is electrically connected to the first pin        D1 through a via. The second end of the first winding segment        922 is electrically connected to the second pin V0 through a        via, and the first end of the second winding segment 921 forms a        third pin S1′, the first pin D1 and the third pin S1′ are both        located on the first side of the transformer module, the second        end of the second winding segment 921 forms a fourth pin GND,        and the second pin V0 and the fourth pin GND are both located on        the second side of the transformer module. When a corresponding        electronic device, such as a switching element, is electrically        connected to the first pin D1 and the third pin S1′, the first        winding segment 922 formed in the first wiring layer and the        second winding segments 921 formed in the second wiring layer        are electrically connected in series. The third metal winding 93        is formed in the third wiring layer and winds around the        magnetic core 91 in a foil structure. In an application        embodiment, the third metal winding 93 can be used as the        primary winding P, and the first metal winding can be used as        the secondary winding S1, for example corresponding to FIG. 3E.

In some embodiments, with reference to FIG. 11B and FIG. 12B, thetransformer module further includes:

-   -   a second metal winding winds around the magnetic core 91 in a        foil structure includes a third winding segment 941 formed in        the first wiring layer and a fourth winding segment 942 formed        in the second wiring layer, and the first end of the third        winding segment 941 is connected to the fifth pin D2 through the        via 95, the second end of the third winding segment 941 is        electrically connected to the second pin V0, and the first end        of the fourth winding segment 942 forms a sixth pin S2′, the        second end of the fourth winding 942 is electrically connected        to the fourth pin GND, and the fifth pin D2 and the sixth pin ST        are both located on the first side of the transformer module. In        an application embodiment, the third metal winding 93 can be        used as the primary winding P, the first metal winding can be        used as the secondary winding S1, and the second metal winding        can be used as the secondary winding S2, for example        corresponding to FIG. 4C.

In some embodiments, after the corresponding electronic device, such asa switch, is electrically connected to the fifth pin D2 and the sixthpin S2′, the third winding segment 941 formed in the first wiring layerand the fourth winding segments 942 formed in the second wiring layerare electrically connected in series.

In some embodiments, the transformer module may include the first metalwinding and the second metal winding, and the third metal winding aswell as the corresponding wiring layer and the insulating layer betweenthe adjacent layers are not highlighted, and the first winding and thesecond winding are respectively used as the primary winding P and thesecondary winding S1 of the transformer module, for example,corresponding to FIG. 3E. This disclosure is not limited to this.

In some embodiments, the vias may be located at about middle points ofthe first metal winding 92 and the second metal winding 91. For example,assuming that both the first winding and the second winding have oneturn, the first winding segment 922, the second winding segment 921, thethird winding segment 941 and the fourth winding segment 942 are abouthalf turn winding around the magnetic core 91, but the presentdisclosure is not limited thereto, and the number of turns of the firstmetal winding and the third metal winding are not limited to one.

In some embodiments, the first side and the second side of thetransformer module are opposite sides. For example, the first side ofthe transformer module may be the upper surface of the transformermodule, and the second side of the transformer module may be the lowersurface of the transformer module. Alternatively, the first side of thetransformer module can be one side of the transformer module and thesecond side of the transformer module can be a different side of thetransformer module. The specific positions of the first side and thesecond side are not limited in the present disclosure.

In some embodiments, the magnetic core is

-shaped, ring-shaped, I-shaped or C-shaped.

In some embodiments, the number of turns of the first metal winding isone turn, the number of turns of the third metal winding is a pluralityof turns to form a spiral type winding around the magnetic core, and thenumber of turns of the second metal winding is one turn.

The distribution of the first pin D1, the fifth pin D2, the third pinS1′, and the sixth pin S2′ of the transformer module will be describedbelow:

As an alternative, FIG. 13A is a top view of a transformer moduleprovided by an embodiment of the present disclosure. As shown in FIG.13A, the number of the first pin D1 is plural, and the number of thefifth pin D2 is plural. And the plurality of first pins D1 and fifthpins D2 are alternately arranged, and the plurality of first pins D1 andthe plurality of fifth pins D2 are located between the third pin S1′ andthe sixth pin S2′.

As another alternative, FIG. 13B is a top view of a transformer moduleprovided by another embodiment of the present disclosure. As shown inFIG. 13B, the first D1, the fifth pin D2, the third pin S1′ and thesixth pin S2′ are both

-shaped, wherein the first pin D1 and the fifth pin D2 are both locatedbetween the third pin S1′ and the sixth pin S2′. When the output pins ofthe second winding is disposed on the first side, the pin located on thefirst side, such as the first pin D1, the fifth pin D2, may also beother shapes such as C-shaped, which are not limited in this disclosure.

FIG. 14A is a bottom view of a transformer module provided by anembodiment of the present disclosure. As shown in FIG. 14A, an outputPIN, such as VOUT, GND, etc., may be formed on a lower surface of thetransformer module. In FIG. 14A, the pin VOUT is placed between two GNDpins. FIG. 14B is a bottom view of a transformer module provided byanother embodiment of the present disclosure. As shown in FIG. 14B, anoutput PIN, such as VOUT, GND, etc., may be formed on the lower surfaceof the transformer module. In FIG. 14B, the multiple pins VOUT aredistributed almost evenly in the one big pin GND.

An embodiment of the present disclosure further provides a transformermodule, since a transformer winding with a foil winded structure iscoated on a transformer magnetic column, so that the equivalentdiameters of respective parts of the winding having the foil windedstructure are similar to each other, and the equivalent impedances aresimilar, thereby achieving the effect of even winding distribution.

Embodiment 8

FIG. 15 is a cross-sectional view of a power module provided by anotherembodiment of the present disclosure. As shown in FIG. 14 , the powermodule includes:

-   -   a transformer module 121 such as the module in the embodiment 6;        and    -   a switch module 122, the switch module 122 and the first side        (for example, an upper surface having a pin) of the transformer        module 121 are in contact and are electrically connected with        the first pin D1, the third pin S1′, the fifth pin D2 and the        sixth pin S2′.

In some embodiments, the switch module 122 includes a board 124 and atleast two power switches (SR) 123. As shown in FIG. 15 , the switchmodule 122 includes power switches (SR) 123, which are disposed in theboard 124 by the molding, embedded process etc. At least one first SR iselectrically connected to the first pin D1 and the third pin S1′, and atleast one second SR is electrically connected to the fifth pin D2 and asixth pin S2′. Wherein, the power switch may be located on the lowersurface of the transformer module, or the power switch may be located onthe upper surface of the transformer module, which is not limited inthis disclosure.

Specifically, the switch module is formed by directly integrating baredies of one or more parallel SRs in a board by an embedded process. Padscorresponding to the transformer module's pins are formed on the lowersurface of the board, and the switch module and the transformer moduleare soldered together to form a power module.

Alternatively, one or more parallel SRs are first welded to the surfaceof the board, and then the switch module is formed by a molding process,and a pad corresponding to the transformer module is formed on the othersurface of the board, and the transformer module is welded on thesurface of the board to form the power module.

Further, the power module further includes: a capacitor module, whereinthe capacitor module is in contact with the second side of thetransformer module and is electrically connected to the second pin andthe fourth pin. Specifically, the power module may further include anLLC primary power unit, a controller, etc., so that the power modulefunctions as an LLC converter. Alternatively, the capacitor moduleincludes an output capacitor Co. The capacitor module may be placed onthe switch module and beside the transformer. When the core of thetransformer is a square or circle shape, the capacitor module may beplace inside the window of the core, e.g. the hole of the core in FIG.3A. Furthermore, the capacitor module may be placed on the board of theswitch module or even embedded inside the board of the switch module.Furthermore, the capacitor module may be placed on one side of thetransformer module e.g. the topside of the transformer module while theswitch module is placed on the other side of the transformer module e.g.the bottom side of the transformer module or the adjacent sides of thetop side of the transformer.

Alternatively, the power module may only include a primary power unit, aresonant unit, a controller, and an output capacitor.

Embodiment 9

FIG. 16 is a top view of a power module provided by another embodimentof the present disclosure. As shown in FIG. 16 , the power moduleincludes:

-   -   a transformer module such as the module in the embodiment 7;    -   at least one first SR is in contact with the first surface        (e.g., an upper surface having a pin) of the transformer module        and is electrically connected to the first pin D1 and the third        pin S1′;    -   at least one second SR is in contact with the first side of the        transformer module (e.g., the upper surface having pin) and is        electrically connected to the fifth pin D2 and the sixth pin        S2′.

Wherein, the SR may be a diode, a MOSFET or an IGBT or the like. Thefirst SR and the second SR may be respectively encapsulated as switchmodules, or may be integrated into a switch module. The disclosure isnot limited to this.

In the embodiment 7 to the embodiment 9, the first metal winding and thesecond metal winding S1 and/or S2 in the circuit diagram shown in FIG. 7may be separately segmented formed to lead out connection ends ondifferent sides of the transformer module.

In some embodiments, such as Embodiment 7 to Embodiment 9, thecorrespondence of the surface-mounted pins is (but not limited to):

-   -   the first pin corresponds to D1, and the third pin corresponds        to S1. According to FIG. 7 and FIG. 12B, correspondingly to the        discontinuity point formed by the segmentations of the first        metal winding, two ends of the switch (for example, a diode) can        be electrically connected to the first pin and the third pin,        respectively, to form a connection relationship between the        switch and segments of the first metal winding in series;    -   the second pin corresponds to V0, and it can be seen from FIG. 7        and the like, the second pin can be an output end of the module;    -   the fourth pin corresponds to GND, and can be used for        connection with the secondary grounding;    -   the fifth pin corresponds to D2, and the sixth pin corresponds        to S2. According to FIG. 7 and FIG. 12B and the like,        correspondingly to the discontinuity point formed by the        segmentation of the second metal winding, the two ends of the        switch (for example, a diode) can be electrically connected to        the fifth pin and the sixth pin, respectively, to form a        connection relationship between the switch and segments of the        first metal winding in series.

However, in the embodiment 7 to the embodiment 9 of the presentdisclosure, for the convenience of description, the electricalconnection points corresponding to the surface-mounted pins aredifferent from the corresponding electrical connection points in theembodiment 1 to the embodiment 4, the present disclosure is not limitedto this.

The transformer module of the foregoing embodiments may also lead thetwo ends of the third metal winding to the pins and may be led out tothe first side, the second side or the other side, and the presentdisclosure is not limited thereto. The shape of the pin is not limitedto the square-shape, C-shape, or other shapes shown in the figures, andcan be flexibly changed according to the actual application.

Each of the metal windings of the transformer module of the foregoingembodiments can flexibly correspond to the primary winding and thesecondary winding of different types of transformers, and can be used,for example, for the ordinary transformer of FIG. 3E or for thesecondary tapped transformer (related to the two secondary windings inseries), and can also be used for transformers with multiple independentsecondary winding, etc., the disclosure is not limited to this.

It should be noted that the above power module is not limited to the LLCconverter, and is also applicable to any circuit including a transformermodule, such as a flyback converter, a full bridge circuit, and thelike.

What is claimed is:
 1. A manufacturing process of a metal winding,comprising: cutting a first metal copper foil to form a connector and apin; performing insulation processing on a surface of at least one ofthe first metal copper foil and a second metal copper foil; bending thefirst metal copper foil to form a first metal winding to cover on amagnetic core; and covering the second metal copper foil at leastpartially on a surface of the first metal copper foil to form a secondmetal winding, and a pin of the first metal winding passes through thesecond metal winding.
 2. The manufacturing process according to claim 1,wherein the performing insulation processing on the surface of at leastone of the first metal copper foil and the second metal copper foil,comprises: performing a first insulation processing on the surface of atleast one of the first metal copper foil and the second metal copperfoil to form an inner base insulating layer; and performing a secondinsulation processing on the metal copper foil that forms the baseinsulating layer, to form an outer additional insulating layer.
 3. Themanufacturing process according to claim 2, wherein an insulation modeof the base insulating layer is electro-deposition.
 4. The manufacturingprocess according to claim 2, wherein the additional insulating layer isan insulating glue locally arranged on the base insulating layer.
 5. Themanufacturing process according to claim 1, wherein before performinginsulation processing on the surface of at least one of the first metalcopper foil and the second metal copper foil, further comprising:performing roughening treatment on the at least one of the first metalcopper foil and the second metal copper foil.
 6. The manufacturingprocess according to claim 1, wherein after performing insulationprocessing on the surface of at least one of the first metal copper foiland the second metal copper foil, further comprising: coating anadhesive layer to the surface of at least one of the first metal copperfoil and the second metal copper foil.
 7. The manufacturing processaccording to claim 1, comprising: winding the second metal winding onthe surface of the first metal winding; and forming a through hole or agap during the winding process to let the pin of the first metal windingpass through the second metal winding.
 8. The manufacturing processaccording to claim 1, comprising: cutting a third metal copper foil toform a through hole or gap; and bending the third metal copper foil tocover a surface of the second metal winding, to form a third metalwinding, wherein the pin of the first metal winding passes through thethrough hole or the gap.